Engage is a novel therapy for late life depression, a disorder that worsens the outcomes of most medical illnesses, promotes disability, increases expense, and complicates medical care by clouding the clinical picture and undermining treatment adherence. Late-life depression has a modest response to pharmacotherapy, and although problem-solving therapy (PST) was found efficacious, it is rarely utilized by community clinicians. Engage targets behavioral domains of late-life depression grounded on neurobiological constructs using behavioral strategies of known efficacy selected for their simplicity. Reward exposure is the principal treatment vehicle of Engage. The first 3 sessions consist of direct reward exposure but the therapists search for barriers in 3 behavioral domains, i.e. negativity bias, apathy, and emotional dysregulation, and add strategies targeting these domains when needed. Engage uses a structured, stepped-care approach and makes personalization part of the treatment itself. The primary hypothesis of the study is that Engage is non-inferior to problem solving therapy (PST), a treatment with demonstrated efficacy in late life depression. Its secondary hypotheses postulate that Engage requires fewer training hours than PST, is non-inferior to PST in reducing disability and in inducing remission of depression. Exploratory analyses will focus on long-term efficacy of Engage (over 26 and 52 weeks) as well as mechanisms and predictors of its effects. The participants will be 300 (150 from each Center) older (>60 years) non-psychotic, non-demented persons with unipolar major depression who will be randomly assigned to 9 sessions of Engage or PST. We bring to this project two research groups with a history of a successful collaboration in 2 two-center R01 supported psychotherapy studies, complementary expertise in clinical biology, intervention development, clinical trials, and experience in directing multicenter studies. This application responds to two IOM reports, which predict that the workforce in geriatrics will be overwhelmed by the aging population, a problem that will reach cataclysmic proportions when the Affordable Care Programs come into being. Older adults seek services in community settings where the providers of initial care for depression are social workers and nurses without in-depth training in psychotherapies. Engage is designed for such clinicians and, therefore, may have broad scalability (used by many professionals) and reach by offering to many depressed seniors access to effective psychotherapy. The stepped approach to personalization used by Engage may make it applicable to other populations.